It's not hard to do Christian music. Anybody can. Anybody. The story behind "Spirit in the Sky" is but one example.
From Wikipedia:
He [Norman Greenbaum] was inspired to write the song after watching Porter Wagoner on TV singing a gospel song. Greenbaum later said : "I thought, 'Yeah, I could do that,' knowing nothing about gospel music, so I sat down and wrote my own gospel song. It came easy. I wrote the words in 15 minutes."
"Spirit in the Sky" contains lyrics about the afterlife, making several references to Jesus. However, Greenbaum, who identifies himself as Jewish, stated that he had no particular religious intentions with the song. He simply wanted to reach a bigger market.
In fifteen minutes he creates a one hit wonder. The point is, consider the "vessel" of the music. People are Christians. I can assure you, God doesn't think much of keychains, mints, movies, video games or posters.
